PURPOSE: To provide an optical rangefinder in which a measuring laser element and a reference laser element can be effectively switched without using a negative power source.

CONSTITUTION: The anode of the laser diode LD1 of a measuring laser element 1 is connected to a power source terminal P1 via a first transistor T1, and connected to a ground terminal via a resistor R11. The anode of the laser diode LD2 of a reference laser element 2 is connected to a power source terminal P3 via a second transistor T2 and connected to the ground terminal via a resistor R21. The cathode of the diode LD1 of the element 1 is connected to a common node NA via a switching diode D11, and the cathode of the diode LD2 of the element 2 is connected to the node ND via a switching diode D21. The node NA is connected to the ground terminal via the secondary winding W2 of a high frequency modulating transformer TR and a resistor R1.